I would think cotton would be cheaper.
I think it has to do with the processing that makes it worth while. Growing hemp like this is not hard. Harvesting is not as back breaking or mechanical (not a lot different than cutting down corm—although you don’t grind it up for silage. The fibers are strong, long, and easily processed.
Its not as fine...but you generally are not sleeping on it—they are used for ropes, sails, etc.
Many farms are using them to produce CBD oil. THAT is akin to bringing in silage. It gets put into a big vat with some chemicals and the oil is extracted—like extracting oil from any plant.